抄録
Recently, workpiece such as jet engine turbine case has been lightened and thinned for low fuel consumption. However, the parts such as jet engine turbine case reduce heat resistance for thinning. So it has been required thinning with heat resistance material. However, cutting heat resistance workpiece of low stiffness that thinning causes contributes chatter vibration. In this study, the phenomenon of chatter vibration is elucidated and predicted. By chatter vibration measurement in several workpiece, chatter vibration frequency and chatter vibration mode in cutting workpiece were found out. Chatter vibration measurement was practiced with 24 displacement sensors to circumferential direction. It turned out chatter vibration is similar to the natural vibration of workpiece and self-excited vibration, which is caused by coupling two vibrations near the cutting tool position. To confirm the relationship between chatter vibration and natural vibration, natural vibration of several workpiece got. By impact test, workpiece’s natural frequency and natural vibration mode were found out. Modal analysis by impact test impacted 36 points of the test piece to circumferential direction. The measurement results turned out that chatter vibration in cutting come from workpiece’s natural vibration. It also turned out that chatter vibration is self-excited vibration, which is caused by coupling two natural vibration near the cutting tool position. From the above, chatter vibration model that include two transfer function and two feedback was created. Prediction of chatter vibration by open loop transfer function is possible by workpiece stiffness and damping by finite element method and experiment.
